Legend:

The first patch (15256.patch on wp-includes/canonical.php) is working form me. Just a small fix, in wp 3.6 this file has 12 more rows, so the patch should be included at row 160-162 instead of 148-150.

2

3

Parent category are redirected well, but anyway these problems remains:

4

5

{{{

6

User goes to URL: /page/2?cat=5

7

Which is a broken/invalid URL. Instead of seeing the listing for page 2, they see the homepage